Navigational device and reversible counter driving mechanism therefor



y 1963 J MITCHELL ET Al. 3,097,793

NAVIGATIONAL bEVICE AND REVERSIBLE COUNTER DRIVING MECHANISM THEREFOR IFiled April 3, 1962 2 Sheets-Sheet 1 FIG-.1

INVENTORS JAMES M/TCHELL ERNEST I'VE/$5 y 1963 J. MITCHELL ETAL3,097,793

NAVIGATIONAL DEVICE AND REVERSIBLE comma DRIVING MECHANISM THEREFORFlled Apml 3 1962 2 Sheets-Sheet 2 FIG. 3

INVENTOR$- JAMES M/TCHELL ERNES T 14 5/55 nrrakemsr United States Patent3,097,793 NAVIGATIONAL DEVICE AND REVERSIBLE COUNTER DRIVING MECHANESMTHEREFOR James I. Mitchell, River Edge, and Ernest Weiss, Maywood, N-ZL,assignors to The'Bendix Corporation, Teterhoro, NJ., a corporation ofDelaware Filed Apr. 3, 1962, Ser. No. 184,767 8 Claims. (Cl. 235-132)This invention relates to a navigational device and to reversiblecounter driving mechanisms therefor, and more particularly to suchmechanisms for latitude or longitude counters.

In navigation counters for providing indications of latitude orlongitude such as those used aboard aircraft, need exists for a counterwherein the indication reverses after a predetermined number of driveshaft revolutions. Such counter permits use of one set of counter wheelsin situations where the counter must indicate both additions andsubtractions. For example, in a longitude indicating counter fornavigation purposes, the counter must add from 000 to 18000', and thensubtract to 000 again. if rotation is continued, it must again add, andrepeat.

Therefore, one object of this invention is to provide a counter havingsimplified means for reversing its direction of indication after apredetermined number of drive shaft revolutions.

Another object of this invention is to provide a counter having areversing mechanism which enables the counter to be positively driven.

Another object of this invention is to provide a counter having areversing mechanism in which the driven gear is never completelydisengaged from the driving mechanism.

Another object of this invention is to provide a navigation counter forindicating both additions and subtractions, requiring only one set ofcounter wheels.

The invention contemplates a reversing mechanism for driving anavigational counter in the forward or reverse directions. The mechanismcomprises a driving gear, a pair of transfer gears one of which ismeshed with both the driving gear and the other transfer gear, and meansfor positioning the trans-fer gears 'so that one or the other transfergear drives the driven gear, which in turn drives the digital counterthrough an output shaft. The means for positioning the transfer gears isdependent upon the number of revolutions made by the driving gear, andpermits thecounter to reach a maximum indication and then count back tozero with continued rotation of the driving gear.

In the drawings:

FIGURE 1 represents a front cutaway view of the counter and reversingmechanism shown in the forward counting position.

FIGURE 2 represents a sectional view on the line A-A of FIGURE 1 whenthe apparatus is in the forward counting position.

FIGURE 3 represents a sectional view on the line A-A of FIGURE 1 whenthe apparatus is in the reverse counting position.

Referring now to FIGURE 1 of the drawings, a driving gear 1 is shownmounted on and drivingly engaged to an input shaft 2. A driven gear 3 isshown mounted on an output shaft 4, which in turn drives a counter showngenerally as 5. The driven gear 3- is driven through a pair of transfergears '6 and 7, which are mounted on a movable arm 8. This arm ispivoted about the input shaft 2, and can be moved to either of twoextreme positions by a cam 9. This cam, which is in slidable contactwith arm 8, is mounted on a shaft and is drivingly engaged to anintermittent gearing group 11 through a pair of driving 3,097 ,7 93Patented July 16, 1963 gears 12 and 13 which are in mesh with eachother. The gearing group 11 is driven by the input shaft 2.

FIGURE 2 more clearly shows the arrangement of pivoted arm 8 andtransfer gears 6 and 7 in driving the counter in the forward direction,while FIGURE 3 shows the same arrangement for driving a counter in thereverse direction.

In operation, input shaft 2 is driven in one rotational direction only(assume this to be clockwise) so long as the craft on which the counteris mounted travels in one general direction only. Driving gear 1, beingconnected to shaft 2, is thus driven in the clockwise direction also.Transfer gear 6 which is constantly in mesh with driving gear 1 is thusdriven counter-clockwise, and transfer gear 7 which is constantly inmesh with transfer gear 6 is driven clockwise. The driven gear 3 mesheswith either transfer gear "6 or 7, depending upon the position of thepivoted arm 8 and is drivingly engaged to the output shaft 4. Theposition of pivoted arm 8 depends upon the rotational position of thecam 9. Cam '9 is positioned by shaft 10 which is driven from theintermittent gearing group 11 through the meshing gears 12 and \13. Theintermittent gearing group 11 is driven by the input shaft 12.

The intermittent gearing group 11 may comprise any of the well knowndevices which produces a rotational output after a certain number ofpredetermined input rotations has occurred. At the proper time, forexample when the counter has reached 18000' longitude, the last transferon the intermittent gearing group drives gear 13 through 90 rotation. Atthat time cam 9 moves the pivoted arm 8 so that gear 3 becomes unmeshedwith gear 6 and meshed with gear 7 thereby rotating the driven gear orcounter wheel 3 in the opposite direction. The counter indication is nowreduced with continued clockwise rotation of the input shaft. Thearrangement and timing of gears 6, 7 and 3 is such that gear 3 is neverunmeshed from both gears 6 and 7 at the same time. Thus there is no lossin synchronism. As input shaft 2 continues to rotate, counter 5 willcontinue to rotate in the reverse direction and intermittent gear group11 will be rotated in accordance with the input shaft. At 9000 longitudegear 13 is rotated again. Cam 9 rotates with gear 13, but due to theshape of the cam the pivoted arm 8 .does not change position. At 0000longitude cam 9 is again rotated, and at this time it moves the pivotedarm 8, putting the appropriate transfer gear 6 in mesh with gear 3,again reversing rotation of the counters. Continued rotation of shaft 2causes the cam to move again at 9000 longitude without actuating thepivoted arm, and at 18000' longitude the action again repeats.

-It should be noted that the operation described could be accomplishedby moving cam 9, or an eccentric only at O0 and 000, but the gear ratioand torque required are reduced if the cam is operated four timesinstead of two. It should also be noted that the input shaft 2 can beoperated in either rotational direction with the same sequence ofoperation.

When the invention is applied to a longitude counter a shutter or flag14 may be attached to the pivoted arm 8 and adjustably positionedthereby for indicating an east and west longitude condition. Similarly,the invention may be applied to a latitude counter and the shutter orflag 14 may be attached to the pivot arm 8 and adjustably positionedthereby to indicate a north and south latitude condition. The inventionmay also be applied to a variation counter or other counters which haveto reverse their direction after a predetermined number of shaftrevolutions.

The invention provides a positively driven counter having means forreversing its directional indication after a predetermined number ofdrive shaft revolutions. The

reversing mechanism is such that the driving gear is never completelydisengaged from the driven gear. Furthermore, the navigation counterprovided by the invention requires only one set of counter Wheels.

Although but one embodiment of the invention has been illustrated anddescribed in detaii, it is to be expressly understood that the inventionis not limited thereto. Various changes can be made in the design andarrangement of the parts without departing from the spirit and scope ofthe invention as the same will now be understood by those skilled in theart.

What is claimed is:

1. A reversing mechanism having an input shaft, a first gear drivinglyengaged by the input shaft, a second gear meshed with the first gear, athird gear meshed with the second gear, a pivoted arm mounting thesecond and third gears, a cam slidably contacting the pivoted arm forpositioning the arm in either of two positions, means for moving the camin accordance with the number of input shaft revolutions, and a drivengear for driving an output shaft meshed with the third gear when the armis in one position and meshed with the second gear when the arm is inthe other position.

2. A reversing mechanism having an input shaft, a driving gear mountedon and driven by the input shaft, a first transfer gear constantly inmesh with the driving gear, a second transfer gear constantly in meshwith the first transfer gear, a pivoted arm mounting the transfer gears,

a cam slidably contacting the pivoted arm for positioning the arm ineither of two positions, means for rotating the cam in accordance withthe number of input shaft revolutions, an output shaft, and a drivengear drivingly engaged to the output shaft and meshing with the secondtransfer gear when the arm is in one position, and meshing with thefirst transfer gear when the arm is in the other position.

3. A reversing mechanism having an input shaft, a driving gear mountedon and driven by the input shaft, a first transfer gear constantly inmesh with the driving gear, a second transfer gear constantly in meshwith the first transfer gear, a pivoted arm mounting the transfer gearsand adapted to be positioned in either of two positions, a cam slidablycontacting the piovted arm for positioning the arm, an intermittentgearing group driven by the input shaft and drivingly engaged to theoam, an output shaft, and a driven gear drivingly engaged to the outputshaft and meshing with the second transfer gear when the arm is in oneposition, and meshing with the first transfer gear when the arm is inthe other position.

4. A reversing mechanism having an input shaft, a driving gear mountedon and driven by the input shaft, a first transfer gear meshing with thedriving gear, a second transfer gear meshing with the first transfergear, a movable arm mounting the first and second transfer gears andadapted to be positioned in more than one position, means slidablycontacting the movable arm for position- Al ing the arm, an intermittentgearing group driven by the input shaft and drivingly engaged to saidmeans, an output shaft, and a driven gear drivingly engaged to theoutput shaft and meshing with the second transfer gear when the arm isin one position and meshing with the first transfer gear when the arm isin a second position.

5 A navigational device comprising a counter, a reversing mechanism fordriving the counter, said reversing mechanism including an input shaft,a driving gear connected to and driven by the input shaft, a pair oftransfer gears, one of the transfer gears meshing with the driving gearand the other transfer gear, means for selectively positioning thetransfer gears in a first position under one operative condition and ina second position under another operative condition, and a driven gearfor driving an output shaft operatively connected to the counter, saiddriven gear meshing with one of the transfer gears when the positioningmeans is in a position to selectively position the transfer gears tosaid first position, and said driven gear meshing with the othertransfer gear When the positioning means is in another position toselectively position the transfer gears to said second position.

6. The combination defined by claim 5 including means operativelyconnected to said positioning means for indicating the prevailingoperative condition.

7. A navigational device comprising a geographical degree counter, areversing mechanism for driving the counter, said reversing mechanismincluding an input shaft, a driving gear connected to and driven by theinput shaft, a pair of transfer gears, one of the transfer gears meshingwith the driving gear and the other transfer gear,

, a movable arm mounting the transfer gears and adapted to be positionedin one position under a first condition of operation and in anotherposition under a second condition of operation, means slidablycontacting the movable arm for positioning the arm, an intermittentgearing group driven by the input shaft and drivingly engaged to saidpositioning means, an output shaft, and a driven gear drivingly engagedto the output shaft and meshing with one transfer gear when the arm isin said one position and meshing with the other transfer gear when thearm is in said second position.

8. The combination defined by claim 7 including means operativelyconnected to said movable arm for indicating the first and secondconditions of operation.

References Cited in the file of this patent UNITED STATES PATENTS1,963,457 Avery June 19, 1934 2,829,532 Togstad Apr. 8, 1958 3,022,946Glass et a1 Feb. 27, 1962 3,027,076 Glass et al Mar. 27, 1962 FOREIGNPATENTS 250,717 Great Britain Apr. 22, 1926

1. A REVERSING MECHANISM HAVING AN INPUT SHAFT, A FIRST GEAR DRIVINGLYENGAGED BY THE INPUT SHAFT, A SECOND GEAR MESHED WITH THE FIRST GEAR, ATHIRD GEAR MESHED WITH THE SECOND GEAR, A PIVOTED ARM MOUNTING THESECOND AND THIRD GEARS, A CAM SLIDABLY CONTACTING THE PIVOTED ARM FORPOSITIONING THE ARM IN EITHER OF TWO POSITIONS, MEANS FOR MOVING THE CAMIN ACCORDANCE WITH THE NUMBER OF INPUT SHAFT REVOLUTIONS, AND A DRIVENGEAR FOR DRIVING AN OUTPUT SHAFT MESHED WITH THE THIRD GEAR WHEN THE ARMIS IN ONE POSITION AND MESHED WITH THE SECOND GEAR WHEN THE ARM IS INTHE OTHER POSITION.